<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>鼠标提示框</title>
    <style>
        #div1{
            width: 200px;
            height: 50px;
            background: #cdcdcd;
            display: none;
        }
    </style>
</head>
<body>
<input type="checkbox" onmouseover="document.getElementById('div1').style.display='block'" onmouseout="document.getElementById('div1').style.display='none'">
<div id="div1">
    提示框：请不要....
</div>

</body>
</html>